What are the key aspects of adrenal gland physiology and clinical anatomy relevant to internal medicine?

From the Guidelines

The adrenal glands are vital endocrine organs with distinct cortical and medullary regions that produce hormones essential for homeostasis and stress response, with the most recent guidelines emphasizing the importance of understanding their physiology and clinical anatomy in managing conditions such as primary adrenal insufficiency and Cushing's syndrome 1.

Key Aspects of Adrenal Gland Physiology

• The adrenal cortex consists of three zones: the zona glomerulosa, zona fasciculata, and zona reticularis, each producing different hormones such as aldosterone, cortisol, and androgens.
• The adrenal medulla produces catecholamines (epinephrine and norepinephrine) that regulate the fight-or-flight response.
• Cortisol production and release is controlled by adrenocorticotropic hormone (ACTH) from the anterior pituitary gland, which is in turn controlled by corticotropin-releasing hormone (CRH) from the hypothalamus.
• The reference range for plasma cortisol is 140–700 nmol.l1 at 0900, but only 80–350 nmol.l1 at midnight, and cortisol production increases in response to stress, such as surgery or critical illness 1.

Clinical Anatomy and Relevant Disorders

• The adrenal glands are located in the retroperitoneal space, with the right gland being triangular in shape and the left gland being crescent-shaped.
• Clinically relevant disorders include primary adrenal insufficiency (Addison's disease), secondary adrenal insufficiency, Cushing's syndrome, primary hyperaldosteronism (Conn's syndrome), pheochromocytomas, and congenital adrenal hyperplasia.
• Primary adrenal insufficiency requires lifelong replacement with hydrocortisone (15-25 mg daily in divided doses) and fludrocortisone (0.05-0.2 mg daily) 1.
• Adrenal crisis requires immediate treatment with IV hydrocortisone 100 mg, and patients with primary adrenal insufficiency should wear Medic Alert identification jewelry and carry a steroid/alert card 1.

From the FDA Drug Label

CLINICAL PHARMACOLOGY Glucocorticoids, naturally occurring and synthetic, are adrenocortical steroids that are readily absorbed from the gastrointestinal tract. Naturally occurring glucocorticoids (hydrocortisone and cortisone), which also have salt-retaining properties, are used as replacement therapy in adrenocortical deficiency states Glucocorticoids cause profound and varied metabolic effects. In addition, they modify the body's immune response to diverse stimuli.

The key aspects of adrenal gland physiology relevant to internal medicine include:

• The production of glucocorticoids, such as hydrocortisone, which have metabolic and anti-inflammatory effects
• The role of glucocorticoids in modifying the body's immune response
• The importance of glucocorticoids in replacement therapy for adrenocortical deficiency states

The key aspects of adrenal gland clinical anatomy relevant to internal medicine include:

• The location and function of the adrenal cortex, which produces glucocorticoids
• The relationship between the adrenal gland and other organ systems, such as the immune system and metabolic pathways

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From the Research

Adrenal Gland Physiology

• The adrenal gland plays a crucial role in regulating various physiological processes, including the production of cortisol, aldosterone, and androgens 3, 4.
• Cortisol is essential for the body's response to stress, regulating blood sugar levels, and maintaining blood pressure 5, 6.
• The adrenal gland is also involved in the production of aldosterone, which helps regulate electrolyte balance and blood pressure 5, 6.

Clinical Anatomy of the Adrenal Gland

• The adrenal gland is located on top of the kidney and is composed of two distinct parts: the adrenal cortex and the adrenal medulla 3, 4.
• The adrenal cortex produces cortisol, aldosterone, and androgens, while the adrenal medulla produces epinephrine and norepinephrine 5, 6.
• Understanding the clinical anatomy of the adrenal gland is essential for diagnosing and treating adrenal disorders, such as Cushing's syndrome and adrenal insufficiency 7.

Medical Therapy for Adrenal Disorders

• Medical therapy is often used to treat adrenal disorders, such as Cushing's syndrome, when surgery is not feasible or has failed 3, 4.
• Adrenal steroidogenesis inhibitors, such as ketoconazole, metyrapone, and osilodrostat, can be used to reduce cortisol production and alleviate symptoms of Cushing's syndrome 5, 6, 7.
• Glucocorticoid receptor antagonists, such as mifepristone, can also be used to treat Cushing's syndrome by blocking the effects of cortisol on the body 3, 4.

Key Aspects of Adrenal Gland Physiology and Clinical Anatomy

• The adrenal gland plays a critical role in regulating various physiological processes, including the production of cortisol, aldosterone, and androgens 3, 4.
• Understanding the clinical anatomy of the adrenal gland is essential for diagnosing and treating adrenal disorders 5, 6, 7.
• Medical therapy, including adrenal steroidogenesis inhibitors and glucocorticoid receptor antagonists, can be used to treat adrenal disorders, such as Cushing's syndrome 3, 4, 5, 6, 7.